Chrome: Pull-apart tabs are a great way to manage windows, but occasionally you have a site you'd like to just keep open. Picture in Picture Viewer does just that by pinning pop-up windows to the bottom of your screen.

The extension works very similar to the Hangouts add-on. Once you create a pop-out window with a tab, you can minimize it to just above your task bar. Hover over it to bring up the title bar, or leave it open above your work. In order to use the extension, you'll first need to enable Panels in Chrome. Simply head to chrome://flags/#enable-panels click "Enable", and restart Chrome.